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Custom attributes for the back wheels and connecting the back rails
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In this lesson, we will create custom attributes to control the spinning of the back wheels, and we'll also constrain down the back rails. We'll get started by first heading over to our Outliner, and we'll make sure that our root joint is going to be stored underneath its group. OK, great. Next, let's select our chest control and create our custom attributes. So we know the first one is going to be displayable. We'll name it extra controls. Following that will be Spin A, and it will be animatable, as well as Spin B. With the chest control selected, let's load up the Connection Editor, making sure it's on output-- which it should be by default. And now we can grab our two back joints, load those in, and connect the Rotate X of Wheel A into Spin A. The same for Spin B. Now we can test these out. OK, great. So everything's working just fine. All right, so next, we can constrain down our back rails. Let's get to our Outliner. We'll grab one of our rail pieces. Hit the up arrow a few times to get to the Rail group. We'll frame it. So they're both contained in one group, and they have each a group of their own. So let's get these constrained down. We could always constrain them to the back tire. So if we were to select our tire mesh and grab one of the rail groups, we can use our Object Offset tool. You'll see that it does inherit values because of the offset that the wheel has, but it's not too big of a deal. I'm not too concerned with these animation controls, as they will only be used to, let's say, finesse the transformation. But it's not going to be taken too far. So if you wanted to, feel free to freeze transforms on those values, but I'm not going to do that. But what I will do is make sure that these curves are easy to grab. So I'm going to set the size to about a value of 70, and then grab the curve shape and just kind of move that over, rotate it down so matches the angle of the rail. Then we can start to translate it over. Another thing you could also do is use the Object Offset tool between the rail group and Joint B. That would also give you zero values. But again, because of how limited the animation will be on these objects, I'm not going to worry too much about that. All, right, great. So one is in place. We can recolor it from here. So that will be red. Let's take care of that. All right, great. So that just leaves us with one more. So we'll grab the tire again, we'll grab the left rail-- here it is, Rail LF. Run our Object Offset tool. Let's set the size to 70. And we will now bring over the shape. Then we'll want to rotate it down and have it match to the control on the right side. So we'll probably want to rotate it down just a little more on the x-axis and translate it over a little bit more, also in the X. I'd say we're good to go here. OK. Great. Well, let's recolor this. That'll be our last task. So find blue. And now we can test these out. So we can start to rotate these around. All right, great. So that's just fine. The pivot is, of course, going to be at the center of the wheel we've constrained them to. If you try to go in and center the pivot, there's going to be offset, of course. So again, we don't necessarily need to do that at all. The animation on these will be very limited. So we can go ahead and call the rails finished. And what I mean by limited is, just to make that very clear, we might use the control to kind of have the rail pop up to be put in place when the robot goes to biped mode. And when he is in truck mode, you may not even see these objects, not until it's time to show them when the robot is again near his final transformation for the shot sequence. So with something like that, it's not a big deal at all to spend too much time on a control logic that will be hardly used. Well, with that said, that's going to finish this lesson off. We do need to dynamically parent the back wheels to the character's torso, so we can work on that in the following lesson.
In this tutorial, we will learn the methods that were used to rig the transforming robot. Throughout these lessons, we will learn the tools and techniques used in the setup process of both our robot and truck. The goal is to break this complex idea down into a simple, and manageable form. We'll cover the rigging process in its entirety, and along this journey, we'll be introduced to several tools that will help make this all come together efficiently. By the end of the course, you'll have the set of skills needed to rig your own transforming robot.